Various methods and cassette holders have been proposed with the intention of facilitating the X-ray examination of handicapped patients.
For instance, U.S. Pat. No. 4,468,803 (Ronci) describes a cassette-holder suspension system which enables the cassette holder to be rotated in mutually different planes so as to enable different types of exposures to be taken. This known system include a clamping device which is maneuvered with the aid of knobs and by means of which the cassette holder and carrier means can be brought to different desired positions, for instance adjacent a table. Vertical adjustments can be made only by releasing the clamping device and mounting said device at the height desired. One drawback with this known apparatus is that it is heavy to manipulate, particularly when moving the apparatus between different positions of application.
U.S. Pat. No. 2,651,725 (McFarland) describes a similar cassette holder device which can be mounted in different positions adjacent a patient's bed. Adjustments require the manipulation or activation of a relatively large number of clamping or tightening members which--as a rule--are located at considerable distance from one another.
Other examples of the known art are found described in U.S. Pat. No. 3,795,815 (Weinstock et al.), which teaches a cassette holder fitted to a wheel chair and SE,B,354 728 (Tidestrom et al.) which teaches a freely transportable device for holding an X-ray film cassette in freely variable positions.
The majority of known arrangements and apparatus have the drawback that a cassette provided with receptor and mounted in a cassette holder can be centered in relation to the radiation source connected only with great difficulty. For instance, it is difficult to position the radiation source in relation to the image receptor so that radiation emitted from said source will pass at right angles to the receptor. Consequently, there is an obvious risk that the images taken will be unsatisfactory and need to be retaken, with subsequent exposure of the patient to unnecessary high dosages of radiation.
These difficulties are accentuated when a grid or screen is placed in the vicinity of the cassette holder--as is normally the case. An important prerequisite with respect to satisfactory images or photographs is that the screen extends perpendicularly to the radiation beam in one plane.